1. Field of the Invention
Embodiments of the invention generally relate to apparatus and methods for expanding a tubular in a wellbore. More particularly, embodiments of the invention relate to a compliant cone system.
2. Description of the Related Art
Hydrocarbon wells are typically initially formed by drilling a borehole from the earth's surface through subterranean formations to a selected depth in order to intersect one or more hydrocarbon bearing formations. Steel casing lines the borehole, and an annular area between the casing and the borehole is filled with cement to further support and form the wellbore. Several known procedures during completion of the wellbore utilize some type of tubular that is expanded downhole, in situ. For example, a tubular can hang from a string of casing by expanding a portion of the tubular into frictional contact with a lower portion of the casing therearound. Additional applications for the expansion of downhole tubulars include expandable open-hole or cased-hole patches, expandable liners for mono-bore wells, expandable sand screens and expandable seats.
Various expansion devices exist in order to expand these tubulars downhole. Typically, expansion operations include pushing or pulling a fixed diameter cone through the tubular in order to expand the tubular to a larger diameter based on a fixed maximum diameter of the cone. However, the fixed diameter cone provides no flexibility in the radially inward direction to allow for variations in the internal diameter of the casing. For instance, due to tolerances, the internal diameter of the casing may vary by 0.25″ or more, depending on the size of the casing. There are also variations of casing weights which have same outer diameters, but different inner diameters. Furthermore, a section of the well might have a single weight casing, but the inner diameter of the casing might have rust buildup, scale buildup, or other types of restrictions of the inner diameter. This variation in the internal diameter of the casing can cause the fixed diameter cone to become stuck in the wellbore, if the variation is on the low side. A stuck fixed diameter cone creates a major, time-consuming and costly problem that can necessitate a sidetrack of the wellbore since the solid cone cannot be retrieved from the well and the cone is too hard to mill up. Further, this variation in the internal diameter of the casing can also cause an inadequate expansion of the tubular in the casing if the variation is on the high side, which may result in an inadequate coupling between the tubular and the casing.
Thus, there exists a need for an improved compliant cone system capable of expanding a tubular while compensating for variations in the internal diameter of the casing.